The present invention relates to an air cleaner that includes a housing, which has an opening, and a filter assembly, which has a filter element and a frame for supporting the filter element. Specifically, the present invention relates to an air cleaner in which the filter is attached to and removed from the housing through the opening.
Conventionally, a type of air cleaner has been known that allows a filter assembly to be installed or removed through an opening of the housing without disassembling the housing (Japanese Laid-Open Patent Publication No. 2008-223485). When the filter assembly is installed in the housing (that is, at an installation position), the sealing portion of the filter element is pressed against the sealing surface of the housing. The air cleaner of the publication has two guide surfaces, which are provided in the housing and extend in the insertion direction of the filter assembly. The guide surfaces have inclined portions, which are inclined to be closer to the sealing surface toward the leading end in the insertion direction. The frame, which supports the filter element, has engaging projections on the side opposite to the sealing portion. The engaging projections are engaged with the guide surfaces. When the filter assembly is inserted into the housing, the engaging projections of the frame are engaged with the guide surfaces of the housing, so that the filter assembly is guided to the installation position along the guide surfaces.
In the air cleaner of Japanese Laid-Open Patent Publication No. 2008-223485, the engaging projections are provided on the side of the frame opposite to the sealing surface. Thus, to insert the filter assembly into the housing through the opening of the housing, the width of the opening needs to be large enough to conform to the projecting dimension of the engaging projections. This unfavorably increases the size of the entire housing. To avoid increase in size of the housing, for example, the diameter of the inlet needs to be reduced to ensure a large width of the opening. This increases the design constraints.